beam beats in X/4 according to minimum durations

libmscore/beam.cpp

@@ -1568,9 +1568,10 @@ void Beam::layout2(QList<ChordRest*>crl, SpannerSegmentType, int frag)
                   ++i;
                   for (; i < n; ++i) {
                         ChordRest* c = crl[i];
+                        ChordRest* p = i ? crl[i - 1] : 0;
                         int l = c->durationType().hooks() - 1;
 
-                        Mode bm = Groups::endBeam(c);
+                        Mode bm = Groups::endBeam(c, p);
                         bool b32 = (beamLevel >= 1) && (bm == Mode::BEGIN32);
                         bool b64 = (beamLevel >= 2) && (bm == Mode::BEGIN64);
 

libmscore/groups.cpp

@@ -66,7 +66,7 @@ static std::vector<NoteGroup> noteGroups {
 //   endBeam
 //---------------------------------------------------------
 
-Beam::Mode Groups::endBeam(ChordRest* cr)
+Beam::Mode Groups::endBeam(ChordRest* cr, ChordRest* prev)
       {
       if (cr->isGrace() || cr->beamMode() != Beam::Mode::AUTO)
             return cr->beamMode();
@@ -76,7 +76,23 @@ Beam::Mode Groups::endBeam(ChordRest* cr)
       const Groups& g = cr->staff()->group(cr->tick());
       Fraction stretch = cr->staff()->timeStretch(cr->tick());
       int tick = (cr->rtick() * stretch.numerator()) / stretch.denominator();
-      return g.beamMode(tick, d.type());
+      Beam::Mode val = g.beamMode(tick, d.type());
+
+      // context-dependent checks
+      if (val == Beam::Mode::AUTO && tick) {
+            // if current or previous cr is in tuplet (but not both in same tuplet):
+            // consider it as if this were next shorter duration
+            if (prev && (cr->tuplet() != prev->tuplet()) && (d == prev->durationType())) {
+                  if (d >= TDuration::DurationType::V_EIGHTH)
+                        val = g.beamMode(tick, TDuration::DurationType::V_16TH);
+                  else if (d == TDuration::DurationType::V_16TH)
+                        val = g.beamMode(tick, TDuration::DurationType::V_32ND);
+                  else
+                        val = g.beamMode(tick, TDuration::DurationType::V_64TH);
+                  }
+            }
+
+      return val;
       }
 
 //---------------------------------------------------------

libmscore/groups.h

@@ -68,7 +68,7 @@ class Groups : public std::vector<GroupNode> {
       void dump(const char*) const;
 
       static const Groups& endings(const Fraction& f);
-      static Beam::Mode endBeam(ChordRest* cr);
+      static Beam::Mode endBeam(ChordRest* cr, ChordRest* prev = 0);
       };
 
 

libmscore/layout.cpp

@@ -1162,34 +1162,76 @@ void Score::layoutStage2()
             Beam* beam       = 0;      // current beam
             Measure* measure = 0;
 
-            Beam::Mode bm = Beam::Mode::AUTO;
+            Beam::Mode bm    = Beam::Mode::AUTO;
             Segment::Type st = Segment::Type::ChordRest;
-            ChordRest* prev = 0;
+            ChordRest* prev  = 0;
+            bool checkBeats  = false;
+            Fraction stretch = 1;
+            QHash<int, TDuration> beatSubdivision;
+
             for (Segment* segment = firstSegment(st); segment; segment = segment->next1(st)) {
                   ChordRest* cr = static_cast<ChordRest*>(segment->element(track));
                   if (cr == 0)
                         continue;
+
+                  // handle grace notes and cross-measure beaming
                   if (cr->type() == Element::Type::CHORD) {
                         Chord* chord = static_cast<Chord*>(cr);
-                  beamGraceNotes(chord, false); // grace before
-                  beamGraceNotes(chord, true);  // grace after
+                        beamGraceNotes(chord, false); // grace before
+                        beamGraceNotes(chord, true);  // grace after
                         // set up for cross-measure values as soon as possible
                         // to have all computations (stems, hooks, ...) consistent with it
                         if (!chord->isGrace())
                               chord->crossMeasureSetup(crossMeasure);
                         }
 
-                  bm = Groups::endBeam(cr);
+                  // if this is a new measure, and it's simple meter (actually X/4),
+                  // then perform a prepass to determine the subdivision of each beat
+                  if (segment->measure() != measure) {
+                        Measure* m = segment->measure();
+                        TimeSig* ts = cr->staff()->timeSig(m->tick());
+                        beatSubdivision.clear();
+                        checkBeats = false;
+                        stretch = ts ? ts->stretch() : 1;
+                        if (ts && ts->denominator() == 4) {
+                              checkBeats = true;
+                              for (Segment* s = m->first(st); s; s = s->next(st)) {
+                                    ChordRest* mcr = static_cast<ChordRest*>(s->element(track));
+                                    if (mcr == 0)
+                                          continue;
+                                    int beat = ((mcr->rtick() * stretch.numerator()) / stretch.denominator()) / MScore::division;
+                                    if (beatSubdivision.contains(beat))
+                                          beatSubdivision[beat] = qMin(beatSubdivision[beat], mcr->durationType());
+                                    else
+                                          beatSubdivision[beat] = mcr->durationType();
+                                    }
+                              }
+                        }
+
+                  // get defaults from time signature properties
+                  bm = Groups::endBeam(cr, prev);
+
+                  // perform additional context-dependent checks
+                  if (bm == Beam::Mode::AUTO) {
+
+                        // check if we need to break beams according to minimum duration in current / previous beat
+                        if (checkBeats && cr->rtick()) {
+                              int tick = (cr->rtick() * stretch.numerator()) / stretch.denominator();
+                              // check if on the beat
+                              if (tick % MScore::division == 0) {
+                                    int beat = tick / MScore::division;
+                                    // get minimum duration for this & previous beat
+                                    TDuration minDuration = qMin(beatSubdivision[beat], beatSubdivision[beat - 1]);
+                                    // re-calculate beam as if this were the duration of current chordrest
+                                    TDuration saveDuration = cr->durationType();
+                                    cr->setDurationType(minDuration);
+                                    bm = Groups::endBeam(cr, prev);
+                                    cr->setDurationType(saveDuration);
+                                    }
+                              }
+
+                        }
 
-                  // end beam at new tuplet or end tuplet, if the next/prev duration type is different
-                  if (cr->tuplet()
-                         && !cr->tuplet()->elements().isEmpty()
-                         && cr->tuplet()->elements().front() == cr
-                         && prev && prev->durationType() == cr->durationType())
-                              bm =  Beam::Mode::BEGIN;
-                  else if (prev && prev->tuplet() && !prev->tuplet()->elements().isEmpty()
-                          && prev->tuplet()->elements().last() == prev && prev->durationType() == cr->durationType())
-                              bm =  Beam::Mode::BEGIN;
                   prev = cr;
 
                   // if chord has hooks and is 2nd element of a cross-measure value

vtest/gen

@@ -39,7 +39,7 @@ else
        accidental-1 accidental-2 accidental-3 accidental-4 accidental-5\
        accidental-6 accidental-7 accidental-8 accidental-9\
        tie-1 tie-2 tie-3 grace-1 grace-2 grace-3 harmony-1 harmony-2 harmony-3 harmony-4\
-       beams-1 beams-2 beams-3\
+       beams-1 beams-2 beams-3 beams-4 beams-5 beams-6 beams-7\
        user-offset-1 user-offset-2 chord-space-1 tablature-1 image-1\
        lyrics-1 lyrics-2 lyrics-3 voice-1"
 fi

vtest/gen.bat

@@ -20,7 +20,7 @@ set SRC=mmrest-1,bravura-mmrest,gonville-mmrest,mmrest-2,mmrest-4,mmrest-5,mmres
  accidental-1,accidental-2,accidental-3,accidental-4,accidental-5, ^
  accidental-6,accidental-7,accidental-8,accidental-9, ^
  tie-1,tie-2,tie-3,grace-1,grace-2,grace-3,harmony-1,harmony-2,harmony-3,harmony-4, ^
- beams-1,beams-2,beams-3, ^
+ beams-1,beams-2,beams-3,beams-4,beams-5,beams-6,beams-7, ^
  user-offset-1,user-offset-2,chord-space-1,tablature-1,image-1, ^
  lyrics-1,lyrics-2,lyrics-3,voice-1